U.S. patent application number 14/611419 was filed with the patent office on 2015-08-06 for device for storing and mixing bone cement.
The applicant listed for this patent is Heraeus Medical GmbH. Invention is credited to Thomas Kluge, Sebastian Vogt.
Application Number | 20150216577 14/611419 |
Document ID | / |
Family ID | 52468884 |
Filed Date | 2015-08-06 |
United States Patent
Application |
20150216577 |
Kind Code |
A1 |
Vogt; Sebastian ; et
al. |
August 6, 2015 |
DEVICE FOR STORING AND MIXING BONE CEMENT
Abstract
A device and/or method stores, mixes, and applies
polymethylmethacrylate bone cement, wherein the device and/or
method comprising a first container for a first pasty component, a
dispensing plunger that is arranged such that it can be shifted in
the first container and serves for extruding the content of the
first container through a dispensing tube opposite from the
dispensing plunger. The dispensing tube can be rotated and shifted
in longitudinal direction through a feed-through in a side of the
first container opposite from the dispensing plunger. A mixing
facility is arranged in the first container, is secured to the
dispensing tube, and is movable in the first container by moving
the dispensing tube. At least one second container for at least one
second component is arranged on the first container, whereby the
internal space of the at least one second container is closed with
respect to the internal space of the first container by means of a
closure, which is openable. The at least one second container is
limited, on the side opposite from the closure, by a dosing
plunger, and whereby at least one limiting surface of the first
container is formed by a mobile volume compensation element.
Inventors: |
Vogt; Sebastian; (Erfurt,
DE) ; Kluge; Thomas; (Vallendar, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Heraeus Medical GmbH |
Wehrheim |
|
DE |
|
|
Family ID: |
52468884 |
Appl. No.: |
14/611419 |
Filed: |
February 2, 2015 |
Current U.S.
Class: |
366/76.7 |
Current CPC
Class: |
A61B 17/8833 20130101;
B01F 15/0278 20130101; B01F 2215/0029 20130101; B01F 15/0225
20130101; B01F 11/0082 20130101; B01F 15/0215 20130101; A61B
2017/8838 20130101; B01F 13/0023 20130101; B01F 11/0054 20130101;
B01F 15/0279 20130101 |
International
Class: |
A61B 17/88 20060101
A61B017/88 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 3, 2014 |
DE |
10 2014 101 305.0 |
Claims
1. A device for storing, mixing, and applying
polymethylmethacrylate bone cement, the device comprising a first
container for a first pasty component of the bone cement, a
dispensing plunger is arranged such that it can be shifted in the
first container and serves for extruding the content of the first
container through a dispensing tube opposite from the dispensing
plunger, wherein the dispensing tube is rotatable and shiftable in
longitudinal direction through a feed-through in a side of the
first container opposite from the dispensing plunger, and a mixing
facility, for mixing the content of the first container, is
arranged in the first container and is secured to the dispensing
tube such that the mixing facility is movable in the first
container by moving the dispensing tube to mix the content of the
first container, wherein at least one second container for at least
one second component of the bone cement is arranged on the first
container, wherein the internal space of the at least one second
container is closed with respect to the internal space of the first
container by means of a closure, which is openable, and wherein the
at least one second container is limited, on the side opposite from
the closure, by a dosing plunger and wherein at least one limiting
surface of the first container is formed by a mobile volume
compensation element.
2. The device according to claim 1, wherein the closure of the at
least one second container is openable by exerting a pressure on
the dosing plunger of at least one second container such that the
first container is then connected to said second container.
3. The device according to claim 1, wherein the mixing facility
comprises at least two mixing vanes that are arranged on the end of
the dispensing tube pointing into the inside of the first container
and that extend radially from the dispensing tube outwards into the
first container.
4. The device according to claim 3, wherein the axial height of the
mixing vane is larger than the maximal outer diameter of the
closure, wherein the hollow space between the mixing vanes
accommodates at least the closure or closures.
5. The device according to claim 1, wherein the device comprises
two second containers, which both are limited on two opposite sides
by one closure each and one dosing plunger each for dispensing the
content of the second containers.
6. The device according to claim 1, wherein the at least one
closure is connected to a ring by means of a flexible fin, wherein
the ring is arranged on the inside of the first container such as
to be mobile about the dispensing tube such that the connection is
axially mobile on the dispensing tube by means of the ring, or
wherein the ring is secured to a guide sleeve that is arranged in
the feed-through for the dispensing tube of the first container and
guides the dispensing tube.
7. The device according to claim 1, further comprising an axially
mobile core is arranged in the dispensing tube and closes the
dispensing tube on the end pointing into the inside of the first
container, wherein, a circumferential sealing ring is arranged on
the core and seals the core with respect to the inner wall of the
dispensing tube.
8. The device according to claim 1, wherein the dispensing plunger
is lockable with respect to the first container on the end of the
first container opposite from the dispensing tube.
9. The device according to claim 1, wherein the volume compensation
element is implemented by means of the dispensing plunger, wherein
the dispensing plunger is designed to be made of two parts
comprising a dispensing plunger in the front and a limiting
plunger, which are supported in the first container such as to be
mobile with respect to each other, and the motion of the front
dispensing plunger out of the first container is limited by the
limiting plunger, wherein the limiting plunger can be locked in the
first container, wherein the limiting plunger comprises a snap-in
mechanism that can be detached from outside and engages an opposite
snap-in mechanism on the first container.
10. The device according to claim 9, wherein a gas passage opening
is provided in at least one of the limiting plunger and between the
limiting plunger and the first container, wherein the gas passage
opening is well-suited for discharging a gas from and filling a gas
in between the front dispensing plunger and the limiting
plunger.
11. The device according to claim 9, wherein a guide element is
arranged on the front dispensing plunger that is guided in a
matching opening in the limiting plunger, wherein the guide element
is preferred to be a cylindrical pin that extends into a matching
cylindrical feed-through in the limiting plunger.
12. The device according to claim 9, wherein a detachable locking
element blocks an axial motion of the front dispensing plunger with
respect to the limiting plunger while the device is in its storage
condition.
13. The device according to claim 1, wherein at least one volume
compensation element is supported as in a bearing through an
elastic spring such as to be mobile with respect to the first
container, whereby the spring pushes the volume compensation
element in the direction of the internal space of the first
container.
14. The device according to claim 1, wherein at least one porous
gas-permeable sealing ring is arranged on the external surface of
the at least one dosing plunger such that a gas exchange between
the space formed by the inner walls of the at least one second
container, the closure, and the dosing plunger, and the surrounding
atmosphere can take place.
15. The device according to claim 1, wherein the at least one
dosing plunger possesses at least one directional snap-in element
that can engage the at least one opposite snap-in mechanism on the
inner surface of the second container in manner such that, after
snapping-in takes place, a backward motion of the dosing plunger
out of the second containers cannot take place.
16. The device according to claim 1, wherein the at least one
second container for the at least one second component of the bone
cement is arranged on the first container on the same side as the
feed-through for the dispensing tube and adjacent to the
feed-through for the dispensing tube.
17. A method for producing a polymethylmethacrylate bone cement
using the device according to claim 1, the method comprising: A)
providing the device, wherein the first container is filled with a
first liquid or pasty component of the PMMA bone cement and the at
least one second container is filled with a second component of the
PMMA bone cement; B) opening the at least one second container by
pushing the dosing plunger forward and dispensing the second
component from the at least one second container into the first
container by further propelling the dosing plunger forward, wherein
the change of volume of the content of the first container upon the
introduction of the second component into the first container is
compensated for through a motion of the at least one volume
compensation element; and C) mixing the two components in the first
container through moving the mixing facility, wherein moving the
mixing facility is associated with the dispensing tube connected to
the mixing facility being pushed into and pulled out of the first
container repeatedly, wherein the change of volume of the content
of the first container during mixing is compensated for through a
motion of the at least one volume compensation element.
18. The method according to claim 17, wherein a core is removed
from the dispensing tube after C), and the method further
comprises: D) applying the mixed bone cement by propelling the
dispensing plunger forward in the first container through the
dispensing tube.
19. The method according to claim 17, wherein the content of the
first container is mixed by moving the mixing facility, which is
connected to the dispensing tube, in the first container by moving
the dispensing tube into and out of the first container, wherein,
in addition, the mixing facility is rotatable in the first
container by rotating the dispensing tube.
20. The method according to claim 17, wherein the interior of the
first container and the interior of the at least one second
container are de-gassed and sterilised before A) occurs, wherein
the limiting plunger, the front dispensing plunger and/or the
volume compensation element are lockable, and subsequently the
first container is filled with a first component of the bone cement
and the at least one second container is filled with a second
component of the bone cement, wherein, concurrently or
subsequently, an antibiotic or a mixture of antibiotics are filled
into at least one second container.
21. The method according to claim 17, wherein the dispensing tube,
after mixing, is moved out in the direction out of the first
container such that the mixing facility touches against the front
inner surface of the first container.
22. The method according to claim 17, wherein the dosing plunger or
dosing plungers, after being pushed in completely, is or are
affixed irreversibly against the at least one second container by
means of a snap-in mechanism.
Description
[0001] The invention relates to a device for storing, mixing, and
applying polymethylmethacrylate bone cement, and to a method for
producing a polymethylmethacrylate bone cement using said
device.
[0002] Accordingly, the subject matter of the invention is a device
for storing and mixing polymethylmethacrylate bone cement that
consists, during storage and prior to mixing, of a liquid or pasty
first component A and separate powdery or pasty second component B,
as well as a method for mixing, and applying if applicable, the two
components and, if desired, an additional pharmaceutical agent.
[0003] Polymethylmethacrylate bone cements (PMMA bone cements) have
been in use in medicine for decades for permanent mechanical
fixation of total joint endoprostheses. These are based on
powder-liquid systems, whereby it is customary to use
methylmethacrylate as monomer. Recently, polymethylmethacrylate
bone cements that are based on the use of cement pastes have been
proposed as well (DE 10 2007 050 762 B3, DE 10 2008 030 312 A1, DE
10 2007 052 116 A1). These bone cements have two cement pastes
stored separately in suitable cartridges. Cartridges of this type
are also often referred to as 2-component cartridges (also as
2K-cartridges). These each contain components of a redox initiator
system, aside from at least one monomer and suitable polymers.
[0004] Methylmethacrylate is the monomer used most commonly in
polymethylmethacrylate bone cements. Redox initiator systems
usually consist of peroxides, accelerators and, if applicable,
suitable reducing agents. Radicals are formed only if all
components of the redox initiator systems act in concert. For this
reason, the components of the redox initiator system are arranged
appropriately in the separate cement pastes such that these cannot
trigger a radical polymerisation. The cement pastes are stable
during storage provided their composition is adequate. Only when
the two cement pastes are mixed to produce a cement dough, the
components of the redox initiator system, previously stored
separately in the two pastes, react with each other forming
radicals which trigger the radical polymerisation of the at least
one monomer. The radical polymerisation then leads to the formation
of polymers while consuming the monomer, whereby the cement dough
is cured. It is customary to use static mixers for mixing the
cement pastes and to attach them for this purpose to the
two-component cartridges filled with the cement pastes.
[0005] When the two cement pastes are extruded from the cartridges,
the two cement pastes are pushed through a static mixer. The
processes of extruding and mixing thus proceed concurrently. Mixing
the cement pastes in the static mixer requires a high extrusion
force since the pressure drop at the mixing elements in the static
mixer is very high. It is therefore necessary to use powerful
pneumatic or mechanical extrusion devices to dispense and optimally
mix the cement pastes. Said pneumatic or mechanical extrusion
devices are elaborate from a technical point of view and expensive.
A less expensive option are the manually-operated extrusion guns,
which are customary with the polymethylmethacrylate bone cements
based on powder-liquid systems, which are suitable for said
cements, but are not sufficiently powerful for extruding and mixing
bone cement pastes through the use of static mixers.
[0006] In conventional two-component cartridges, the volume ratio
of component A to component B is 1:1, 1:2, and 1:10. The more the
volumes of the components to be mixed through the use of static
mixers differ, the more difficult it is to generate a homogeneously
mixed bone cement paste. For this reason, very many mixing spirals
are needed for larger volume ratios. The larger the number of
mixing spirals needed, the larger is the pressure drop in the
static mixer during the mixing process. One pasty component needs
to be present, whereas the second component can be either liquid or
powdery or pasty as well. The components and/or pastes need to be
pressed through the static mixer by a very large force. Due to the
nature of manually-operated extrusion devices, the maximally
possible extrusion force is limited.
[0007] The Semkit.RTM. system is time-proven in the adhesives and
sealants industry for many years. It involves storing a paste in a
storage container. A second liquid component is present in a
stirring rod, separated from the paste through a valve that is
integrated into the stirring rod. Actuating the valve allows the
liquid to flow into the paste which can then be mixed by hand.
[0008] Said system is disadvantageous, though, in that the valve
system is suitable for viscous media only. The customary monomer of
pasty polymethylmethacrylate bone cements, i.e. methylmethacrylate,
cannot be separated permanently from the paste by this valve.
Moreover, volume fluctuations arising during the axial mixing
motion of the stirring rod in non-compressible pastes are
compensated for in this system, firstly, in that the cartridges are
soft and can change shape and/or expand and, secondly, in that the
feed-through for the stirring rod is not absolutely tight such that
mixed paste can leak and a small amount of air can also be drawn
into the mixed paste. For pasty polymethylmethacrylate bone
cements, solid cartridges of a stable shape are required, since the
relatively viscous pasty polymethylmethacrylate bone cement dough
can be extruded from storage containers and/or cartridges only
through very large extrusion forces. Moreover, with bone cements,
it is not feasible to use a mixing system, in which inadvertent
leakage of small amounts of paste takes place and in which there is
the possibility that air is drawn into the paste. This would not
only impair the cleanliness in the operating room, but also
mechanically weaken the cement dough through the introduction of
air since air bubbles in the cured cement act as fissure initiation
sites and thus reduce the stability of the cured bone cement.
Therefore, the Semkit.RTM. system cannot be used for pasty
polymethylmethacrylate bone cements.
[0009] Accordingly, it is the object of the invention to overcome
the disadvantages of the prior art. In particular, a simple and
inexpensive device for storing and mixing polymethylmethacrylate
bone cement is to be developed that can be used to store at least
one polymethylmethacrylate bone cement component while excluding
air, whereby it shall be feasible, after mixing of the cement
components, to dispense the cement dough with customary,
inexpensive, manually-operated cementing guns. In this context, the
main component of the polymethylmethacrylate bone cement shall be a
cement paste and the second component can be pasty or can
preferably be present as a powder. The mixing process must not be
associated with any inadvertent leakage of cement dough and no air
must be drawn into the cement dough due to volume fluctuations
during the mixing process. The device shall also be suitable to
ensure safe mixing of the two pastes at a volume ratio of the
components from 1:10 to 01:30 in order to obtain homogeneous cement
dough. It shall be possible to store the two components of the bone
cement separately and to combine them safely by actuating a closure
device.
[0010] Another aim of the present invention is to ensure that, to
the extent possible, no residues from opening or cutting a film
open, such as with a packaging or a protective film, can remain in
the cement dough. The opening, through which the second component
is fed into the main component, shall have a reproducible
cross-sectional surface area, which, to the extent possible, does
not change while the components are being mixed. Moreover, the
opening of the dispensing tube towards the container, in which the
components are being mixed, shall always have a pre-determined
cross-sectional surface area. Said cross-sections shall not be
altered if at all possible.
[0011] It is another object of the invention to provide for the
dispensing tube of the device to be safely patent for the cement
dough after the cement components are mixed and the closure is
opened, whereby the opening of the dispensing tube must be secured
against being blocked by the opened closure while the cement dough
is being extruded. Moreover, a method for mixing pasty
polymethylmethacrylate bone cements involving the use of the device
to be developed is to be provided.
[0012] The objects of the invention are met by a device for
storing, mixing, and applying polymethylmethacrylate bone cement,
comprising a first container for a first pasty component of the
bone cement, a dispensing plunger that is arranged such that it can
be shifted in the first container and serves for extruding the
content of the first container through a dispensing tube opposite
from the dispensing plunger, whereby the dispensing tube is
arranged such that it can be rotated and shifted in longitudinal
direction through a feed-through in a side of the first container
opposite from the dispensing plunger, and a mixing facility for
mixing the content of the first container, whereby the mixing
facility is arranged in the first container and is secured to the
dispensing tube such that the mixing facility can be moved in the
first container by moving the dispensing tube in order to mix the
content of the first container, whereby at least one second
container for at least one second component of the bone cement is
arranged on the first container, whereby the internal space of the
at least one second container is closed with respect to the
internal space of the first container by means of a closure, which
can be opened, and [whereby] the at least one second container is
limited, on the side opposite from the closure, by a dosing
plunger, and whereby at least one limiting surface of the first
container is formed by a mobile volume compensation element.
[0013] According to the invention, the components for the bone
cement can be present in the first container and the at least one
second container.
[0014] Preferably, the first component is free of air. Preferably,
the second component is powdery or pasty, particularly preferably
it is a self-sterilising paste. Self-sterilising pastes can
contain, for example, hydrogen peroxide. Preferably, one or more of
the at least one second container(s) contain(s) a self-sterilising
paste of the type described in EP 2 596 812 A1.
[0015] Basically, for implementation of the spirit of the
invention, it is sufficient to have the dispensing tube arranged
opposite from the dispensing plunger with respect to the operative
connection. A geometrically exact juxtaposition is not required.
The same applies to the closure and the dosing plunger of the at
least one second container. As before, the opposite side is given
by the transmission of the pressure and therefore no geometrically
opposite positioning of the dosing plunger and closure is required
in order to implement the spirit of the invention.
[0016] A volume compensation element can preferably be implemented
through one or two cylinders that are mobile in axial direction in
the cylindrical internal space of the first container.
Alternatively or in addition, a volume compensation element can
just as well be formed through a flexibly deformable skin or
membrane.
[0017] According to a preferred refinement, the invention can just
as well provide that the closure of the at least one second
container can be opened by exerting a pressure on the dosing
plunger of said second container such that the first container is
then connected to said second container.
[0018] By this means, the second container or second containers
is/are easy to open towards the first container from outside.
Simultaneously, the same pressure that opens the closure or
closures can be used to transfer the content of the second
container or contents of the second containers into the first
container. Accordingly, just a single actuation of the dosing
plungers or dosing plunger is required to open the closure or
closures and to dispense the content of the second container or
contents of the second containers into the first container.
[0019] It can also be preferred, according to the invention, that
the invention provides the closure to be a closure stopper or a
closure cap, which, in its closed state, is plugged into an opening
in a separating wall between the first container and the at least
one second container, such that it closes said opening.
[0020] According to a refinement, the invention can provide the
mixing facility to comprise at least two mixing vanes that are
arranged on the end of the dispensing tube pointing into the inside
of the first container and that extend radially from the dispensing
tube outwards into the first container.
[0021] Mixing vanes shaped as described can ensure that the entire
content of the first container is mixed completely.
[0022] In this context, the invention can provide the axial height
of the mixing vane to be larger than the maximal outer diameter of
the closure, whereby the hollow space between the mixing vanes is
sufficient to accommodate at least the closure or closures.
[0023] This ensures that the closures or closure do/does not block
the dispensing tube from being pulled out by being plugged-in
between the mixing vanes and the front side of the internal space
of the first container which contains the feed-through for the
dispensing tube, and prevent the dispensing tube from being pulled
out further from the first container.
[0024] According to a preferred refinement of the device according
to the invention, the invention can provide the device to comprise
two second containers, which both are limited on two opposite sides
by one closure each and one dosing plunger each for dispensing the
content of the second containers.
[0025] A third component and/or an additional pharmaceutical agent
can be supplied to the cement mixture with said second containers.
Preferably, the invention can also provide a third component,
preferably an antibiotic or mixture of antibiotics, is or can be
filled into a second container by means of a filling aid, such as,
for example and preferably according to the invention, a dosing
funnel, whereby the filling aid comprises a filling socket that
fits to the end of the second container that points away from the
first container. Accordingly, according to the invention, the
device can comprise said filling aid, which would need to be
arranged into the then open end of the second container or of one
of the second containers instead of a dosing plunger.
[0026] The invention further proposes the at least one closure to
be connected to a ring by means of a deformable connection, in
particular a flexible fin, whereby the ring is arranged on the
inside of the first container such as to be mobile about the
dispensing tube such that the connection is axially mobile on the
dispensing tube by means of the ring, or whereby the ring is
secured to a guide sleeve that is arranged in the feed-through for
the dispensing tube of the first container and guides the
dispensing tube.
[0027] Preferably, according to the invention, the ring as such can
be provided to be a sleeve. Having the ring prevents the closure or
closures from being freely mobile in the first container and from
interfering with the mixing, the mobility of the mixing facility
and/or the extrusion of the cement dough. In particular, the
closures cannot become placed over the termination opening into the
dispensing tube and thus impede the flow of the mixed cement
dough.
[0028] Alternatively, the closure or closures can just as well be
secured to the mixing facility such that the closure or closures,
and thus the second container or second containers, are also opened
by pushing the dispensing tube into the first container. In order
to prevent the at least one second container from opening
inadvertently, the invention can provide the dispensing tube to be
affixable or affixed, in detachable manner, to the at least one
second container by means of a locking device.
[0029] In order to prevent inadvertent leakage of bone cement or
starting components, the invention can provide an axially mobile
core to be arranged in the dispensing tube and to close the
dispensing tube on the end pointing into the inside of the first
container, whereby, preferably, a circumferential sealing ring is
arranged on the core and seals the core with respect to the inner
wall of the dispensing tube.
[0030] As a result, it can be ensured that no non-finished and
non-mixed cement dough enters the dispensing tube from the at least
one second container or even leaks from the dispensing tube while
the component(s) is/are being mixed and filled in.
[0031] The invention also proposes that it is feasible, with the
closure opened, that the content of the second container or
contents of the second containers can be transferred into the first
container by means of the dosing plunger, and that the contents of
the first container and second container or second containers can
then be mixed with each other in the first container by means of
the mixing facility.
[0032] This ensures that the device is easy to operate.
[0033] To simplify the operation of devices according to the
invention, the invention can just as well provide that the
dispensing plunger can be or is locked with respect to the first
container, preferably can be locked or is locked on the end of the
first container opposite from the dispensing tube.
[0034] This prevents any inadvertent interfering motion of the
dispensing plunger while the first container is being filled and
while the first container is being sterilised.
[0035] The invention can particularly preferably provide the first
container to comprise a cylindrical internal space, and the
dispensing plunger in the internal space of the first container to
be of a shape that matches the footprint of the cylindrical
internal space.
[0036] The cylindrical shape is the easiest shape by means of which
the first container and thus the device can be implemented. A
cylindrical internal space shall be understood geometrically to
mean a general cylinder with any footprint, i.e. not just a
cylinder with a circular footprint. The internal space can
therefore be a straight cylinder having any footprint, i.e.
including a non-circular or round footprint. However, a cylindrical
internal space having a circular footprint is preferred according
to the invention. Said geometry renders all regions of the first
container particularly well-reachable for the mixing facility. The
dispensing plunger is then also cylindrical and preferably touches
against the walls of the cylindrical internal space of the first
container by means of a seal. Particularly preferably, a wiper is
arranged on the side of the dispensing plunger facing the internal
space and serves to prevent the mixed bone cement paste from being
pushed past the dispensing plunger and from exiting on the rear of
the device when the dispensing plunger is propelled forward. In the
case of the preferred circular cylinder geometry of the first
container, the mixing facility has mixing vanes that are equal in
size or preferably slightly smaller (for example smaller by 0.1 mm)
than the internal diameter of the cylindrical internal space.
[0037] The cylindrical geometry with a circular footprint is the
simplest for the design of the device. It is particularly preferred
that the external surface of the first container also is
cylindrical accordingly, and that at least 90% of the wall share
the same thickness. Then, the first container can essentially be
built laterally as a simple tube.
[0038] Moreover, the invention can just as well provide the second
container or second containers to comprise a cylindrical internal
space and can provide the dosing plunger in the internal space of
the second container or second containers to be of a shape that
matches the foot print of the cylindrical internal space or can
provide the dosing plungers to be of a shape that matches the foot
print of the corresponding cylindrical internal spaces.
[0039] Said symmetry has the same advantages as the symmetry of the
first container.
[0040] An even more particularly preferred embodiment of the
present invention can be implemented by implementing the volume
compensation element by means of the dispensing plunger, whereby
the dispensing plunger is designed to be made of two parts, i.e. a
dispensing plunger in the front and a limiting plunger, which are
supported in the first container such as to be mobile with respect
to each other, and the motion of the front dispensing plunger out
of the first container is limited by the limiting plunger, whereby
the limiting plunger can be locked in the first container, whereby
the limiting plunger preferably comprises a snap-in mechanism that
can be detached from outside and engages an opposite snap-in
mechanism on the first container.
[0041] Since the dispensing plunger needs to be arranged in the
first container such as to be mobile anyway, it can also be
utilised as mobile volume compensation element. Accordingly, there
is no need to have a separate additional mobile part, which allows
the costs of producing the device to be kept low.
[0042] In this context, a gas passage opening can be provided in
the limiting plunger and/or a gas passage opening can be provided
between the limiting plunger and the first container, whereby the
gas passage opening(s) is or are well-suited for discharging a gas
from and filling a gas in between the front dispensing plunger and
the limiting plunger.
[0043] This can ensure that the gas between the front dispensing
plunger and the limiting plunger can be evacuated and that the
intervening space can be sterilised with a sterilising gas.
Moreover, a compressed gas can also be supplied into the
intervening space in order to push the front dispensing plunger
into the inside of the first container in order to extrude the
content of the first container and/or the ready-mixed cement
dough.
[0044] Devices according to the invention, in which the dispensing
plunger is used as volume compensation element, can be provided
appropriately to have a guide element arranged on the front
dispensing plunger that is guided in a matching opening in the
limiting plunger, whereby the guide element is preferred to be a
cylindrical pin that extends into a matching cylindrical
feed-through in the limiting plunger.
[0045] As a result of this measure, the front dispensing plunger
does not become lodged or cants while moving and does not block
further motion in the first container.
[0046] A further refinement of the invention proposes a detachable
locking element to block an axial motion of the front dispensing
plunger with respect to the limiting plunger while the device is in
its storage condition.
[0047] As a result, any filling of the first container and any
sterilisation of the device is not made more difficult by the two
parts (the front dispensing plunger and the limiting plunger)
moving with respect to each other.
[0048] A refinement of the present invention proposes the front
dispensing plunger to be supported, such as to be mobile, with
respect to the limiting plunger by means of an elastic spring,
whereby the spring is arranged between the front dispensing plunger
and the limiting plunger and pushes the front dispensing plunger
into the internal space of the first container. Preferably, the
spring is arranged about the guide element and/or the pin if either
of these is present.
[0049] As a result, the front dispensing plunger is actively
restored to the desired position by the elastic spring upon
repeated changes of the volume of the first container, which may be
caused, for example, by mixing the content of the first container
by repeatedly pushing and pulling the dispensing tube with the
mixing facility in and out.
[0050] It is particularly advantageous, according to the invention,
to provide the space between the shiftable dispensing plunger and
the limiting plunger to have a volume that is at least equal in
size to the sum of, firstly, the difference in volume between the
volume of the part of the dispensing plunger that is situated in
the first container when the dispensing tube is fully inserted into
the first container and when the dispensing tube is fully pulled
out of the first container plus, secondly, the volume of the second
component or the volume of the internal space of the one second
container or the volumes of the internal spaces of the second
containers.
[0051] This structure ensures that the dispensing plunger, as
volume compensation element, can accommodate the full change of
volume of the content of the first container.
[0052] A further refinement of the invention, preferred according
to the invention, can provide at least one volume compensation
element to be supported as in a bearing by means of an elastic
spring such as to be mobile with respect to the first container,
whereby the spring pushes the volume compensation element in the
direction of the internal space of the first container.
[0053] As a result, the volume compensation element is actively
restored to the original position by the elastic spring upon
repeated changes of the volume of the first container which are
arise due to the mixing of the content of the first container by
repeatedly pushing and pulling the dispensing tube with the mixing
facility in and out.
[0054] The invention also proposes to arrange at least one porous
gas-permeable sealing ring on the external surface of the at least
one dosing plunger such that a gas exchange between the space
formed by the inner walls of the at least one second container, the
closure, and the dosing plunger, and the surrounding atmosphere can
take place.
[0055] The invention can also provide, alternatively or in
addition, the dosing plunger to comprise at least one gas-permeable
porous disc such that a gas exchange between the space formed by
the inner walls of the at least one second container, the closure,
and the dosing plunger, and the surrounding atmosphere can take
place.
[0056] As a result, the content of the at least one second
container can be evacuated and sterilised with a sterilising
gas.
[0057] Another refinement of the present invention can provide the
at least one dosing plunger to possess at least one directional
snap-in element that can engage the at least one opposite snap-in
mechanism on the inner surface of the second container in
appropriate manner such that, after snapping-in takes place, a
backward motion of the dosing plunger out of the second
container(s) cannot take place.
[0058] This ensures that, upon extrusion of the ready-made cement
mixture by means of the dispensing plunger, the cement mixture is
dispensed exclusively through the dispensing tube and does not leak
through the at least one second container.
[0059] Moreover, the invention proposes to arrange the at least one
second container for the at least one second component of the bone
cement on the first container on the same side as the feed-through
for the dispensing tube, in particular adjacent to the feed-through
for the dispensing tube.
[0060] This design simplifies the operation of the device. This
applies especially when the dispensing plunger is used as volume
compensation element and when a screw cap, screwed onto a thread
about the dispensing tube or about the feed-through for the
dispensing tube, is used to propel the dosing plungers.
[0061] A refinement of the present invention also proposes to
insert a separate third hollow cylinder into the at least one
second container, which preferably is arranged on the head of the
first container, whereby the third hollow cylinder contains a
component of the bone cement and is closed by means of a dosing
plunger and a closure stopper.
[0062] Preferably, the closure stopper is connected to the second
hollow cylinder by means of a mobile fin.
[0063] This measure simplifies the production of the device since
the separate third hollow cylinder can be filled with a component
of the bone cement and/or an additive for the bone cement, and
since the separate third hollow cylinder needs to be inserted into
one of the second containers only after it is filled.
[0064] The invention can just as well provide a separate hollow
cylinder to be arranged in a second container, which is arranged on
the head (i.e. in the front) of the first container, and to contain
a third component of the bone cement and to be closed by means of a
closure stopper and a dosing plunger, whereby the closure stopper
is connected to the first hollow cylinder by means of a mobile fin,
and to arrange a further separate hollow cylinder in a further
second container, which is arranged on the head of the first
container, and to contain a pharmaceutical agent and to be closed
by means of a closure stopper and a dosing plunger, whereby the
closure stopper is connected to the second hollow cylinder by means
of a mobile fin.
[0065] Moreover, the invention proposes the axially mobile
dispensing plunger to possess a guide element that engages a
guidance of the dispensing plunger.
[0066] In this context, the invention can also provide the second
dosing plunger to possess a guidance for the guide element of the
dispensing plunger and the second dosing plunger to possess at
least one snap-in element that can be detached by applying external
pressure and affixes the second dosing plunger to the inside wall
of the first container in reversible manner.
[0067] The objects of the present invention are also met through a
method for producing a polymethylmethacrylate bone cement (PMMA
bone cement) using a device according to any one of the preceding
claims, characterised by the steps of:
A) providing the device, whereby the first container is filled with
a first liquid or pasty component of the PMMA bone cement and the
at least one second container is filled with a second component of
the PMMA bone cement, which preferably is powdery or pasty; B)
opening the at least one second container by pushing the dosing
plunger forward and dispensing the second component from the at
least one second container into the first container by further
propelling the dosing plunger forward, whereby the change of volume
of the content of the first container upon the introduction of the
second component into the first container is compensated for
through a motion of the at least one volume compensation element;
and C) mixing the two components in the first container through
moving the mixing facility, whereby moving the mixing facility is
associated with the dispensing tube connected to the mixing
facility being pushed into and pulled out of the first container
repeatedly, whereby the change of volume of the content of the
first container during mixing is compensated for through a motion
of the at least one volume compensation element.
[0068] In this context, the invention can provide a core to be
removed from the dispensing tube after step C), and then a step D)
to take place, in which the mixed bone cement is applied by
propelling the dispensing plunger forward in the first container
through the dispensing tube.
[0069] Moreover, a refinement of the method according to the
invention proposes that the content of the first container is mixed
by moving the mixing facility, which is connected to the dispensing
tube, in the first container by moving the dispensing tube into and
out of the first container, whereby, in addition, the mixing
facility preferably is being rotated in the first container by
rotating the dispensing tube.
[0070] As a result, the method can be implemented particularly
easily, since only one mobile element, i.e. the dispensing tube, is
being operated such that the likelihood of incorrect operation is
reduced. Moreover, it is easy to mix the components even under
adverse conditions outside of an orderly surgical room.
[0071] Moreover, methods according to the invention can be provided
such that the interior of the first container and the interior of
the at least one second container are de-gassed and sterilised
before step A) takes place, whereby it is preferred for this
purpose to lock the limiting plunger, the front dispensing plunger
and/or the volume compensation element, and subsequently the first
container is filled with a first component of the bone cement and
the at least one second container is filled with a second component
of the bone cement, whereby it is preferred, concurrently or
subsequently, to fill an antibiotic or a mixture of antibiotics
into at least one second container.
[0072] This ensures the sterility of the content. This allows
infections of the patient to be prevented.
[0073] According to a preferred refinement of the method according
to the invention, the invention can just as well provide the
dispensing tube, after mixing, is moved out (or pulled out) in the
direction out of the first container such that the mixing facility
touches against the front inner surface of the first container.
[0074] Moreover, the invention can provide the dosing plunger or
dosing plungers, after being pushed in completely, to be affixed
irreversibly against the at least one second container by means of
a snap-in mechanism.
[0075] Methods according to the invention can therefore provide the
implementation of the method to involve the compensation of changes
of volume occurring in the first container by the volume
compensation element.
[0076] Provided the dispensing plunger is lockable by a locking
element, the invention can provide the locking element of the
dispensing plunger to be detached, such that the dispensing plunger
is freely mobile in axial direction, before the content of the at
least one second container is transferred to or introduced into the
first container.
[0077] The invention is based on the surprising finding that
designing the device according to the invention and using the
method according to the invention allows to easily provide an
option for mixing and application of a bone cement whose individual
components have a disparate mixing ratio of 1:10 and more.
Providing second containers or a second container that are or is
easy to handle and easily accessible and contain(s) the lower dosed
component, said component can be added by the user easily and with
little effort. Due to the volume compensation element, the cement
paste or the starting components can be prevented from leaking from
the device and from thus contaminating the surroundings and/or the
bone cement when they are being combined. The structure can be
manufactured, sterilised, and filled with the starting components
both easily and inexpensively. Moreover, providing a dosing funnel
can enable the user to add further additives such as, for example,
a special mixture of antibiotics or other pharmaceutical agents
customised for the patient.
[0078] One example of the structure of a device according to the
invention is, for example, a device for storing and mixing
polymethylmethacrylate bone cement composed of
a) a cylindrical storage container comprising a first container
that is filled with pasty component A; b) a dispensing tube that
can be moved axially through a feed-through on the head of the
dispensing container, whereby the dispensing tube contains two or
more mixing vanes on the side facing the first container; c) a core
plugged into the dispensing tube that closes, in reversible manner,
the dispensing tube on the side of the tube facing the first
container; d) at least one hollow cylinder that is connected to the
first container, whereby the hollow cylinder forms a second
container that is filled with component B; e) a closure stopper
that can be pushed out axially only in the direction of the first
container and separates the first container from the second
container; f) at least one dosing plunger that is arranged in the
at least one hollow cylinder such as to be axially mobile; g)
whereby the second container is limited in the hollow cylinder by
means of the closure stopper and the dosing plunger; h) an axially
shiftable dispensing plunger (the front dispensing plunger) that
limits the first container; i) a second plunger (the limiting
plunger) that is arranged behind the front dispensing plunger,
whereby said second plunger is affixed on the inner cartridge wall
(the first container) by means of a snap-in element that can be
detached by an external influence, whereby the second plunger
possesses at least one gas passage opening that connects the space
of the first container between the axially shiftable front
dispensing plunger and the surrounding atmosphere; and j) whereby
the volume of the space between the shiftable front dispensing
plunger and the second limiting plunger is at least equal in size
to the sum of the volumes of component B and the dispensing tube
when the dispensing tube is at maximal immersion depth in the first
container.
[0079] It is preferred in this context to provide two hollow
cylinders with one closure stopper and one axially mobile dosing
plunger each.
[0080] A method according to the invention can be implemented, for
example, through
a) firstly, detaching the locking element of the dispensing plunger
such that the dispensing plunger is freely mobile in axial
direction; b) by pushing the at least one dosing plunger in the
direction of the closure stopper, whereby the stopper exits from
the hollow cylinder into the first container, in which pasty
component A is situated, and pressing component B into the first
container into pasty component A by moving the dosing plunger
further; c) by affixing, by means of the snap-in mechanism, the
dosing plunger irreversibly in the hollow cylinder after it reaches
the inside of the head of the storage container; d) subsequently
mixing component B and pasty component A to form cement dough C by
moving the dispensing tube axially and tangentially by means of the
mixing vanes; e) moving the dispensing tube in the direction of the
head of the storage container, after the mixing took place, such
that the mixing facility touches against the inner surface of the
storage container (the first container); f) by then pulling the
core out of the dispensing tube and then moving the limiting
plunger and the front dispensing plunger situated above it in the
direction of the head of the storage device, whereby cement dough C
is extruded from space through the dispensing tube into the
surroundings; and by g) compensating for the changes of volume of
the first container during steps b, c, and d, which are caused by
component B being squeezed in and by the dispensing tube including
the mixing vanes being pushed in and pulled out, through axial
motions of the front dispensing plunger.
[0081] Another method according to the invention can be
implemented, for example, through
a) firstly, detaching the locking element of the dispensing plunger
such that the dispensing plunger is freely mobile in axial
direction; b) by pushing the first dosing plunger in the direction
of the closure stopper, whereby the stopper exits from the hollow
cylinder into the first container, in which pasty component A is
situated, and pressing a pharmaceutical agent into the first
container into pasty component A by moving the first dosing plunger
further; c) by affixing, by means of the snap-in mechanism, the
first dosing plunger irreversibly in the hollow cylinder after it
reaches the interior of the head of the storage container; d) by
then pushing the second dosing plunger in the direction of the
closure stopper, whereby the stopper exits from the hollow cylinder
into the first container, in which pasty component A is situated,
and by pressing component B1 into the first container into pasty
component A by moving the second dosing plunger further; e) by
affixing, by means of the snap-in mechanism, the dosing plunger
irreversibly in the hollow cylinder after it reaches the interior
of the head of the storage container; f) by subsequently mixing
component B1 and the pharmaceutical agent and pasty component A to
form cement dough C by moving the dispensing tube including the
mixing facility axially and tangentially; g) by moving the
dispensing tube in the direction of the head of the storage
container, after the mixing took place, such that the mixing
facility touches against the inner surface of the storage
container; h) by then pulling the core out of the dispensing tube
and then moving the limiting plunger and the front dispensing
plunger situated above it in the direction of the head of the
storage device, whereby cement dough C is extruded from the first
container through the dispensing tube into the surroundings; and i)
by compensating for the changes of volume of the first container
during steps b, c, and d, which are caused by the pharmaceutical
agent and component B1 being squeezed in and by the dispensing tube
including the mixing vanes being pushed in and pulled out, through
axial motions of the front dispensing plunger.
BRIEF DESCRIPTION OF THE DRAWINGS
[0082] Further exemplary embodiments of the invention shall be
illustrated in the following on the basis of eight schematic
figures, though without limiting the scope of the invention. In the
figures:
[0083] FIG. 1 shows a schematic side view of a device according to
the invention with a filling funnel inserted;
[0084] FIG. 2 shows a schematic side view of the device according
to FIG. 1 rotated by 90.degree.;
[0085] FIG. 3 shows a schematic cross-sectional view of a part of a
device according to the invention;
[0086] FIG. 4 shows a schematic perspective cross-sectional view of
the device shown in FIG. 3;
[0087] FIG. 5 shows a schematic perspective cross-sectional view of
the device shown according to FIGS. 3 and 4, in which a dosing
plunger is pushed in;
[0088] FIG. 6 shows a schematic perspective view of a two-part
dispensing plunger, designed as volume compensation element, for a
device according to the invention;
[0089] FIG. 7 shows a schematic cross-sectional view of a two-part
dispensing plunger, designed as volume compensation element, for a
device according to the invention; and
[0090] FIG. 8 shows a schematic side view of a device according to
the invention with a dosing plunger pushed in.
[0091] For simplification, identical or similar components in the
figures are identified through the same reference numbers to some
extent. Sectioned surfaces are shown by hatching.
[0092] FIG. 1 shows a schematic side view of a device 1 according
to the invention, and FIG. 2 shows a schematic side view of the
device 1 according to FIG. 1 rotated by 90.degree.. Device 1 is a
bone cement cartridge system 1 for retaining, storing, mixing, and
applying a bone cement and/or the components thereof. Device 1 and
the parts thereof are essentially made of plastic material, for
example by means of injection moulding. Device 1 comprises a
cylindrical first container 2 that has a cylindrical internal
space. A pasty first component and/or a main component of a medical
multi-component bone cement, preferably of a PMMA bone cement, is
present in the internal space of the first container 2.
[0093] Two further (second) containers 4, 5 are arranged on the
front of the first container 2 (on the top in FIGS. 1 and 2) and
are each connected to the first container 2 by means of an opening
(not shown), whereby closures (not shown) are arranged in the two
openings that close the openings and thus separate the first
container 2 from the two containers 4, 5 and/or the internal spaces
thereof. Said second container 4 is closed by means of a dosing
plunger 6 on the side of the second container 4 opposite to the
opening. The first second container 4 is filled with a second
component of the bone cement that can be powdery or pasty.
[0094] The second dosing plunger (not shown) of the other second
container 5 has been taken out and a dosing funnel 8 has been
inserted into the thus opened other second container 5 (the second
second container 5) by means of which a pharmaceutical agent (such
as, for example, an antibiotic), a mixture of agents, a further
component of the bone cement or a mixture thereof can be filled
into the other second container 5. Subsequently, the second dosing
plunger is inserted in the same manner as the first dosing plunger
6. The dosing funnel 8 allows additional components and agents to
be filled in shortly before the application during a surgery.
[0095] A dispensing tube 10 is guided through a gas-tight
feed-through (not shown) of the first container 2, between the two
openings of the second containers 4, 5 and/or between the two
second containers 4, 5 into the first container 2. The dispensing
tube 10, by means of which the finished bone cement mixture is
being applied, is mobile in longitudinal direction (from top to
bottom and vice versa in FIGS. 1 and 2) and is supported in the
gas-tight feed-through like in a bearing such that it can rotate.
On the inside of the first container 2, a mixing facility (not
shown) is arranged on the dispensing tube 10 in the form of two or
more mixing vanes that extend radially away from the dispensing
tube 10 in the direction of the inner walls of the first container
2 to or almost to the inner walls of the first container 2. As a
result, the dispensing tube 10 can be moved in order to mix the
content of the first container 2. The front opening (on the top in
FIGS. 1 and 2) of the dispensing tube 10 is closed by means of a
handle part 12. The handle part 12 is connected to a rod on the
inside of the dispensing tube 10 that extends up to a core (not
shown) on the end of the dispensing tube 10 that points towards the
inside of the first container 2, and is connected to said core. The
core seals the dispensing tube 10. The dispensing tube 10
preferably consists of a transparent plastic material such that it
can be recognised from outside how far the mixed bone cement dough
already advanced in the dispensing tube 10 when the finished bone
cement mixture is being applied through the dispensing tube 10.
[0096] The core can be pulled out of the dispensing tube 10 by
means of the handle part 12 and the rod to open the dispensing
opening, i.e. the device 1 is thus made ready for application of
the mixed bone cement dough.
[0097] A screw cap 14 having an internal thread (not shown) is
arranged about the dispensing tube 10 and can be screwed onto a
matching external thread 16 on the front of the first container 2.
Provided the dosing plungers 6 are plugged-in into both containers
4, 5, the dosing plungers 6 can be pushed into the second
containers 4, 5 by placing-on the screw cap 14, by pressing-on the
screw cap, and by screwing-on the screw cap 14. The content of the
two second containers 4, 5 thus transmits a pressure acting on the
closures of the two second containers 4, 5 to the first container 2
such that the closures in the openings to the first container 2 are
detached from said openings and are pushed into the first container
2. This opens the two second containers 4, 5 towards the first
container 2.
[0098] Propelling the dosing plungers 6 further transfers the
content of the two second containers 4, 5 into the content of the
first container 2. FIG. 8 shows a side view of the device 1 with
the dosing plunger 6 being pushed-in to the full extent. The
resulting increase in volume in the first container 2 is taken up
by means of a volume compensation element. Presently, a two-part
dispensing plunger 18, inserted on the floor-side (on the bottom in
FIGS. 1 and 2) into the first container 2, is provided as volume
compensation element. The first front dispensing plunger (not
shown) of the dispensing plunger 18, which points further into the
inside of the first container 2, is supported like in a bearing
such as to be mobile in the longitudinal direction of the symmetry
axis of the first container 2. A steel spring (not shown) pushing
the front dispensing plunger into the inside of the first container
2 is arranged between the floor-side second part (the limiting
plunger) of the dispensing plunger 18 and the front dispensing
plunger of the dispensing plunger 18. Provided as volume
compensation element, the dispensing plunger 18 is thus capable of
taking up volume changes caused by the contents of the second
containers 4, 5 being filled in, as well as those volume changes
generated by the dispensing tube 10 being pushed in and pulled out
of the first container 2. The function of the two-part dispensing
plunger 18 is illustrated in more detail through FIG. 6 and FIG.
7.
[0099] A butterfly screw 20 for operation of a locking element is
provided on the dispensing plunger 18, whereby the two parts of the
dispensing plunger 18 can be locked to each other in detachable
manner by rotating the butterfly screw 20 such that the front
dispensing plunger and the limiting plunger are no longer axially
mobile with respect to each other. The locking is advantageous for
filling of the first container 2 and for sterilising by evacuation
and filling with a sterilising gas. In order to prevent the front
dispensing plunger from moving inadvertently, the locking element
preferably stays closed until right before the contents of the two
second containers 4, 5 are introduced into the first container 2.
The butterfly screw 20 is pulled out and removed prior to
dispensing the ready-mixed cement dough from the device 1 and/or
the dispensing plunger 18. The limiting plunger then has a
rear-side surface onto which a pestle of a cement gun can exert a
pressure in order to propel both parts of the dispensing plunger 18
and thus expel the content (the finished bone cement) from the
first container 2. Alternatively, just the front dispensing plunger
can be propelled by means of a compressed gas. For this purpose,
one or more gas feed-throughs must be present in the limiting
plunger.
[0100] FIG. 3 shows a magnified schematic cross-sectional view of a
part of the device 1 according to the invention, and FIG. 4 shows a
schematic perspective cross-sectional view of the part shown in
FIG. 3. Device 1 comprises a first container 2 that has a
cylindrical internal space. A cylindrical dispensing plunger (not
shown in FIGS. 3 to 5), which fits in the direction of the symmetry
axis and/or longitudinal axis of the internal space of the first
container 2 and is mobile, but detachably lockable, is arranged on
the floor-side in the cylindrical internal space (on the bottom in
FIGS. 3 to 5).
[0101] The front side (on the top in FIGS. 3 to 5) of the first
container 2 is partly covered by two second containers 4, 5. A
stopper 22 is provided in each of the openings of the second
containers 4, 5 towards the first container 2 and separate the
second containers 4, 5 from the first container 2, or separate the
internal spaces thereof, as the case may be. The two second
containers 4, 5 are closed on their front by two dosing plungers 6,
24. The external shape of the dosing plungers 6, 24 corresponds to
the inner shape of the second containers 4, 5 and the dosing
plungers 6, 24 can be shifted in longitudinal direction of the
second containers 4, 5 (from top to bottom in FIGS. 3 to 5) such
that the contents of the second containers 4, 5 can be pressed into
the first container 2 by means of the dosing plungers 6, 24.
[0102] The two second containers 4, 5 and the dosing plungers 6, 24
are cylindrical and have a kidney-shaped footprint, i.e. a
kidney-shaped cross-section perpendicular to the cylinder axis, and
are arranged about the dispensing tube 10 to be adjacent to each
other.
[0103] Pushing the dosing plungers 6, 24 inwards pushes the
stoppers 22 out of the openings to the first container 2. Then the
content of the second containers 4, 5 is pushed into the first
container 2. In this context, FIG. 5 shows a schematic perspective
cross-sectional view of the part of device 1 that is also shown in
FIGS. 3 and 4, in which a dosing plunger 24 is pushed in fully into
one of the second containers 5. Snap-in elements 26 are provided on
the top of the dosing plungers 6, 24 and engage opposite snap-in
mechanisms 28 on the outer surface of the second containers 4, 5.
As soon as the dosing plungers 6, 24 are pushed in fully, the
snap-in elements 26 snap into the opposite snap-in mechanisms 28
such that the dosing plungers 6, 24 can no longer be moved out of
the second containers 4, 5. This ensures that the finished bone
cement mixture cannot be extruded into and through the second
containers 4, 5 when the content of the first container 2 is being
pressed out by means of the dispensing plunger.
[0104] Instead, the finished bone cement mixture is extruded
through the dispensing tube 10 and can be applied by means of the
tip thereof to the bone of a patient during surgery. For this
purpose, a core 30 that closes the dispensing tube 10 from inside
must first be pulled out of the dispensing tube 10 by means of a
rod 32 that is connected to the core 30. The core 30 is sealed with
respect to the inner wall of the dispensing tube 10 by means of a
circumferential seal 34 such as, for example, an O-ring made of
rubber. The core 30 is situated on the end of the dispensing tube
10 that points into the inside of the first container 2.
[0105] This end of the dispensing tube 10 also has mixing vanes 36
arranged on it, which extend radially away from the dispensing tube
10 in the direction of the inner walls of the first container 2 and
approach the same up to 0.1 mm or even more closely.
[0106] The two stoppers 22 are connected by means of two fins 38 to
a ring 40 that is arranged about the dispensing tube 10. Having the
fins 38 and ring 40 present ensures that the stoppers 22 cannot
move freely in the first container 2 and, in the process, prevent
or impair the mixing of the content of the first container 2 by
means of the mixing facility 36. Moreover, having the ring 40 and
fins 38 prevents the stoppers 22 from inadvertently becoming placed
in front of the junction leading into the dispensing tube 10, which
would impair the flow of the finished bone cement mixture into the
dispensing tube 10.
[0107] A screw cap 14 is arranged in front of the two dosing
plungers 6, 24 such that it can rotate about the dispensing tube
10. The screw cap 14 has an internal thread 42 that can be screwed
onto an external thread 16 in front of the two second containers 4,
5, whereby the dosing plungers 6, 24 are pushed into the second
containers 4, 5 during this process. The dosing plungers 6, 24
comprise gas-permeable openings (not shown).
[0108] The various individual parts of the device 1 are sealed with
respect to each other by sealing rings 44, 45 made of rubber such
that the first container 2 can be evacuated and such that the
content of the first container 2 cannot be extruded through the
intervening spaces when a pressure is applied by means of the
dispensing plunger.
[0109] The dispensing tube 10 is guided through a guide sleeve 46
into the first container 2 and is sealed by means of a sealing ring
44. The head of the cartridge (of the first container 2) at which
the two second containers 4, 5 are provided, is plugged, in the way
of a cap, onto the cylinder by means of a snap-in mechanism that
forms the wall of the first container 2, and on the guide sleeve
46. The head of the cartridge is sealed with respect to the
cylinder wall of the first container 2 by means of a sealing ring
45.
[0110] FIG. 6 shows a schematic perspective view of a two-part
dispensing plunger 18 of a device according to the invention that
is provided as volume compensation element, and FIG. 7 shows a
schematic cross-sectional view of a two-part dispensing plunger 18
that is provided as volume compensation element, in the manner in
which it can be inserted into the devices 1 according to FIGS. 1 to
5 and 8. The first part on the front (on the top in FIG. 6) of the
dispensing plunger 18, i.e. the front dispensing plunger 50, is
supported, such as to be mobile, against the second part in the
rear, i.e. the limiting plunger 52 of the dispensing plunger 18. An
elastic spring 54 made of steel or made of an elastic plastic
material is arranged between the two parts 50, 52 of the dispensing
plunger 18 and pushes the front dispensing plunger 50 into the
interior of the first container, i.e. upwards in FIGS. 6 and 7.
[0111] The limiting plunger 52 has a gas-permeable feed-through
(not shown) provided in it that enables the air to escape from the
intervening space between the two parts 50, 52 in order to allow
the intervening space to be sterilised with a sterilising gas and,
if applicable, in order to propel the front dispensing plunger 50
by means of a gas pressure without having to move the limiting
plunger 52. A circumferential wiper lip 56 is arranged on the upper
edge of the front dispensing plunger 50. The wiper lip 56 touches
against the inner walls of the first container 2, while the front
dispensing plunger 50 is inserted into the first container 2, and
ensures that no residual bone cement stays behind in the first
container 2 and/or that no bone cement can leak from the rear of
the device 1.
[0112] A locking element that can be detached by means of a
butterfly screw 20 can be used to lock the front dispensing plunger
50 with respect to the limiting plunger 52. Multiple snap-in
elements 58, which are arranged on the outer circumference of the
limiting plunger 52 and are bendable radially inward, such as
projecting springs and/or strips, connect the limiting plunger 52
to opposite snap-in means (not shown) that are arranged
correspondingly on the inner walls of the first container 2, such
as, for example, a circumferential groove, such that the limiting
plunger 52, once inserted, can no longer be removed easily from the
first container 2.
[0113] A butterfly screw 20 for operation of the locking element is
provided on the dispensing plunger 18, whereby the two parts 50, 52
of the dispensing plunger 18 can be locked to each other in
detachable manner by rotating the butterfly screw 20 such that the
front dispensing plunger 50 and the limiting plunger 52 are no
longer axially mobile with respect to each other. The locking
mechanism is advantageous for filling of the first container 2 and
for sterilising of the intervening space between the two parts 50,
52 by evacuation and filling-in a sterilising gas. In order to
prevent the dispensing plunger 50 from moving inadvertently with
respect to the limiting plunger 52, the locking element preferably
stays closed until right before the contents of the two second
containers 4, 5 are introduced into the first container 2.
[0114] The butterfly screw 20 is pulled out and removed prior to
dispensing the ready-mixed cement dough from the device and/or the
dispensing plunger 18. The limiting plunger 52 then has a rear-side
surface onto which a pestle of a cement gun can exert a pressure in
order to propel both parts 50, 52 of the dispensing plunger 18 and
thus expel the content (the finished bone cement mixture) from the
first container 2. Alternatively, just the front dispensing plunger
50 can be propelled by means of a compressed gas. For this purpose,
one or more gas feed-throughs must be present in or adjacent to the
limiting plunger 52.
[0115] A guide element 60 in the form of a cylindrical pin having a
square or rectangular footprint is attached on the cylinder axis of
the front dispensing plunger 50 and extends into a recess of the
limiting plunger 52. The guide element 60 prevents the front
dispensing plunger 50 from tilting and thus from canting.
[0116] The cross-sectional view according to FIG. 7 shows how the
locking element works and how it can be operated by means of the
butterfly screw 20. The butterfly screw 20 has a shaft with two
different diameters. The thinner shaft in the front can be pushed
into a fitting thinner recess in the guide element 60 of the front
dispensing plunger 50. The thinner shaft can be locked to the guide
element 60 by means of a first bayonet closure 62. A second bayonet
closure 64 is provided on the thicker shaft and can lock the
thicker shaft to the limiting plunger 52. Thus, using the locking
element made up of the two parts of the shaft, the bayonet closures
62, 64, and the butterfly screw 20, the front dispensing plunger 50
can be firmly connected to the limiting plunger 52.
[0117] The snap-in means 58 of the limiting plunger 52 are arranged
on bendable fins and, when inserted, engage a circumferential
groove on the inner walls of the first container 2, whereby the
groove is arranged in the region of the rear of the first container
2. The limiting plunger 52 comprises gas passages (not shown)
through which a gas can be evacuated from or supplied between the
front dispensing plunger 50 and the limiting plunger 52.
[0118] By means of the fins and the snap-in means 58, the limiting
plunger 52 can be detached manually from outside from the walls of
the first container 2. For this purpose, the opposite snap-in means
and/or the groove on the inner wall of the first container 2 is
arranged so close to the rear end of the first container 2 that the
rear part of the fins projects beyond the rear edge of the first
container 2.
[0119] FIG. 8 shows a schematic side view of a device 1 according
to the invention with a dosing plunger inserted. The screw cap 14
has been screwed fully onto the external thread. In the process,
the contents of the opened second containers 4, 5 were fully
transferred into the first container 2.
[0120] By rotating and pushing and pulling the dispensing tube 10
in and out, the mixing element connected to it is moved in the
interior of the first container 2 and the content of the first
container 2 is being mixed. After mixing, the dispensing tube 10 is
pulled out of the internal space of the first container 2 to the
stop (upwards in FIG. 7). During this process, the loose stoppers
22 become placed against intervening spaces of sufficient size
between the mixing vanes 36 of the mixing facility 36.
Subsequently, the core 30 in the interior of the dispensing tube 10
is pulled out of the dispensing tube 10 by means of the handle part
12 and the device 1 thus becomes opened towards the outside.
[0121] Propelling the dispensing plunger 18 or the front dispensing
plunger 50 into the first container 2 dispenses the ready-mixed
bone cement dough from the first container 2 via the dispensing
tube 10 such that it can be applied.
[0122] The structure of the device 1 and its parts is in many parts
symmetrical about a symmetry axis that is vertical with respect to
the figures and/or with respect to a plane of symmetry, in which
said symmetry axis is situated.
[0123] The features of the invention disclosed in the preceding
description and in the claims, figures, and exemplary embodiments,
can be essential for the implementation of the various embodiments
of the invention both alone and in any combination.
LIST OF REFERENCE NUMBERS
[0124] 1 Device/bone cement cartridge system [0125] 2 First
container [0126] 4 First second container [0127] 5 Second second
container [0128] 6, 24 Dosing plunger [0129] 8 Dosing
funnel/filling aid [0130] 10 Dispensing tube [0131] 12 Handle part
[0132] 14 Screw cap [0133] 16 External thread [0134] 18 Dispensing
plunger [0135] 20 Butterfly screw [0136] 22 Lid/closure [0137] 26
Snap-in element [0138] 28 Opposite snap-in means [0139] 30 Core
[0140] 32 Rod [0141] 34 Seal [0142] 36 Mixing vane/mixing facility
[0143] 38 Fin [0144] 40 Ring [0145] 42 Internal thread [0146] 44,
45 Sealing ring [0147] 46 Guide sleeve [0148] 50 Front dispensing
plunger [0149] 52 Limiting plunger [0150] 54 Spring [0151] 56 Wiper
lip [0152] 58 Snap-in means/spring [0153] 60 Guide element/pin
[0154] 62 Bayonet closure with guide element [0155] 64 Bayonet
closure with limiting plunger
* * * * *